Electronic battery tester

ABSTRACT

An electronic battery tester for testing a storage battery includes test circuitry configured to provide an output based upon a selected test criteria. Additionally, circuitry is provided to assist in balancing batteries used in a string of multiple batteries.

This is a Divisional of application Ser. No. 09/703,270, filed Oct. 31,2000 which claims priority to Provisional Application Ser. No.60/163,013, filed Nov. 1, 1999 by David Vonderhaar and Michael E. Troyand entitled AUTOMOTIVE BATTERY CHARGING SYSTEM TESTER.

BACKGROUND OF THE INVENTION

The present invention relates to storage batteries. More specifically,the present invention relates to a battery system tester for testingstorage batteries.

Many attempts have been made to test storage batteries. One techniquewhich has been pioneered by Dr. Keith S. Champlin and Midtronics, Inc.of Burr Ridge, Ill. relates to measuring the conductance of batteries todetermine their condition. This technique is described in a number ofUnited States patents, for example, U.S. Pat. No. 3,873,911, issued Mar.25, 1975, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE; U.S.Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin, entitledELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 4,816,768, issued Mar.28, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE; U.S.Pat. No. 4,825,170, issued Apr. 25, 1989, to Champlin, entitledELECTRONIC BATTERY TESTING DEVICE WITH AUTOMATIC VOLTAGE SCALING; U.S.Pat. No. 4,881,038, issued Nov. 14, 1989, to Champlin, entitledELECTRONIC BATTERY TESTING DEVICE WITH AUTOMATIC VOLTAGE SCALING TODETERMINE DYNAMIC CONDUCTANCE; U.S. Pat. No. 4,912,416, issued Mar. 27,1990, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE WITHSTATE-OF-CHARGE COMPENSATION; U.S. Pat. No. 5,140,269, issued Aug. 18,1992, to Champlin, entitled ELECTRONIC TESTER FOR ASSESSING BATTERY/CELLCAPACITY; U.S. Pat. No. 5,343,380, issued Aug. 30, 1994, entitled METHODAND APPARATUS FOR SUPPRESSING TIME VARYING SIGNALS IN BATTERIESUNDERGOING CHARGING OR DISCHARGING; U.S. Pat. No. 5,572,136, issued Nov.5, 1996, entitled ELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATIONFOR LOW STATE-OF-CHARGE; U.S. Pat. No. 5,574,355, issued Nov. 12, 1996,entitled METHOD AND APPARATUS FOR DETECTION AND CONTROL OF THERMALRUNAWAY IN A BATTERY UNDER CHARGE; U.S. Pat. No. 5,585,728, issued Dec.17, 1996, entitled ELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATIONFOR LOW STATE-OF-CHARGE; U.S. Pat. No. 5,592,093, issued Jan. 7, 1997,entitled ELECTRONIC BATTERY TESTING DEVICE LOOSE TERMINAL CONNECTIONDETECTION VIA A COMPARISON CIRCUIT; U.S. Pat. No. 5,598,098, issued Jan.28, 1997, entitled ELECTRONIC BATTERY TESTER WITH VERY HIGH NOISEIMMUNITY; U.S. Pat. No. 5,757,192, issued May 26, 1998, entitled METHODAND APPARATUS FOR DETECTING A BAD CELL IN A STORAGE BATTERY; U.S. Pat.No. 5,821,756, issued Oct. 13, 1998, entitled ELECTRONIC BATTERY TESTERWITH TAILORED COMPENSATION FOR LOW STATE-OF-CHARGE; U.S. Pat. No.5,831,435, issued Nov. 3, 1998, entitled BATTERY TESTER FOR JISSTANDARD; U.S. Pat. No. 5,914,605, issued Jun. 22, 1999, entitledELECTRONIC BATTERY TESTER; U.S. Pat. No. 5,945,829, issued Aug. 31,1999, entitled MIDPOINT BATTERY MONITORING; U.S. Pat. No. 6,002,238,issued Dec. 14, 1999, entitled METHOD AND APPARATUS FOR MEASURINGCOMPLEX IMPEDANCE OF CELLS AND BATTERIES; U.S. Pat. No. 6,037,777,issued Mar. 14, 2000, entitled METHOD AND APPARATUS FOR DETERMININGBATTERY PROPERTIES FROM COMPLEX IMPEDANCE/ADMITTANCE; U.S. Pat. No.6,051,976, issued Apr. 18, 2000, entitled METHOD AND APPARATUS FORAUDITING A BATTERY TEST; U.S. Pat. No. 6,081,098, issued Jun. 27, 2000,entitled METHOD AND APPARATUS FOR CHARGING A BATTERY; U.S. Pat. No.6,091,245, issued Jul. 18, 2000, entitled METHOD AND APPARATUS FORAUDITING A BATTERY TEST; U.S. Pat. No. 6,104,167, issued Aug. 15, 2000,entitled METHOD AND APPARATUS FOR CHARGING A BATTERY; and U.S. Pat. No.6,137,269, issued Oct. 24, 2000, entitled METHOD AND APPARATUS FORELECTRONICALLY EVALUATING THE INTERNAL TEMPERATURE OF AN ELECTROCHEMICALCELL OR BATTERY.

With the advent of accurate battery testing, it has become apparent thatin some instances the battery testing technique may not be appropriatefor the particular purpose of the battery or configuration of multiplebatteries.

SUMMARY OF THE INVENTION

An electronic battery tester for testing a storage battery, includes adynamic measurement circuit configured to measure at least one dynamicparameter of the battery. A memory is configured to store a plurality oftest criteria and an input is configured to receive input data relatedto a selected test criteria. A test circuit provides an output relatedto battery condition as a function of the dynamic parameter and theselected test criteria. In another aspect, a memory is configured tostore a first dynamic parameter from the measurement circuitry relatedto a first battery of a battery pack. Balance circuitry provides anin-balance output if a second battery in the pack has a dynamicparameter which is substantially equal to the first dynamic parameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of a battery tester in accordancewith the present invention.

FIG. 2 is a simplified diagram illustrating a tester in accordance withthe present invention.

FIG. 3 is a simplified diagram illustrating a tester in accordance withthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a simplified block diagram of a battery tester 10 inaccordance with one embodiment of the present invention coupled to avehicle 12. Vehicle 12 includes a battery 14 having positive andnegative terminals, an alternator with internal regulator 16, variousvehicle loads 18, and a starter motor 20. In operation, battery 14provides power to starter 20 and vehicle loads 18 when the engine invehicle 12 is not running. When the engine in vehicle 12 is running,alternator 16 is used to power vehicle loads 18 and provide a chargingcurrent to battery 14 to maintain the charge of battery 14.

Charging system tester 10 includes a microprocessor 30 which controlsoperation of tester 10 and provides instructions and test resultinformation to an operator through, for example, a display 32. Tester 10includes a battery testing section 34 which is illustrated generally asconductance amplifier 36. Section 34 operates in accordance with, forexample, the conductance based battery testing techniques described inChamplin U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin,entitled ELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 3,909,708,issued Sep. 30, 1975, to Champlin, entitled ELECTRONIC BATTERY TESTINGDEVICE; U.S. Pat. No. 4,816,768, issued Mar. 28, 1989, to Champlin,entitled ELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 4,825,170,issued Apr. 25, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTINGDEVICE WITH AUTOMATIC VOLTAGE SCALING; U.S. Pat. No. 4,881,038, issuedNov. 14, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICEWITH AUTOMATIC VOLTAGE SCALING TO DETERMINE DYNAMIC CONDUCTANCE; U.S.Pat. No. 4,912,416, issued Mar. 27, 1990, to Champlin, entitledELECTRONIC BATTERY TESTING DEVICE WITH STATE-OF-CHARGE COMPENSATION;U.S. Pat. No. 5,140,269, issued Aug. 18, 1992, to Champlin, entitledELECTRONIC TESTER FOR ASSESSING BATTERY/CELL CAPACITY; U.S. Pat. No.5,343,380, issued Aug. 30, 1994, entitled METHOD AND APPARATUS FORSUPPRESSING TIME VARYING SIGNALS IN BATTERIES UNDERGOING CHARGING ORDISCHARGING; U.S. Pat. No. 5,572,136, issued Nov. 5, 1996, entitledELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATION FOR LOWSTATE-OF-CHARGE; U.S. Pat. No. 5,585,728, issued Dec. 17, 1996, entitledELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATION FOR LOWSTATE-OF-CHARGE; U.S. Pat. No. 5,598,098, issued Jan. 28, 1997, entitledELECTRONIC BATTERY TESTER WITH VERY HIGH NOISE IMMUNITY; U.S. Pat. No.5,821,756, issued Oct. 13, 1998, entitled ELECTRONIC BATTERY TESTER WITHTAILORED COMPENSATION FOR LOW STATE-OF-CHARGE. Section 34 is illustratedin very simplified form and conductance amplifier 36 provides an outputto an analog to digital converter 38 which is related to the internalconductance of battery 14.

A DC voltage sensor 40 includes voltage scaling resistors 42 and 44 andis coupled to battery 14 to provide an output to analog to digitalconverter 38 which is representative of the DC voltage across battery14. Further, an AC ripple detector amplifier 46 is coupled to battery 14through capacitors 48 and 50 and provides an output to analog to digitalconverter 38 which is representative of the AC ripple voltage acrossbattery 14.

Microprocessor 30 controls analog to digital converter 38 to selectwhich of the three inputs to digitize. Microprocessor 30 includesfirmware, memory, and a software program in accordance with theinvention. The user input 54 is coupled to microprocessor 30 to providethe information to microprocessor 30 from an operator.

Preferably, tester 10 is portable such that it may be easily movedbetween vehicles or otherwise transported. Portability of tester 10 isachieved because tester 10 does not require large internal carbon pileloads to load the battery charging system.

Instead, as described herein, tester 10 utilizes loads internal to thevehicle 12 in testing the charging system. Further, the battery testerperformed by tester 10 is in accordance with the non-load batterytesting technique as described above.

In another aspect of the present invention, microprocessor 30 includes amemory which is capable of storing a number of different decision makingalgorithms or test criteria. The particular test criteria or algorithmcan be selected through user input 54. For example, in one aspect, thetest criteria is selected based upon the particular type of battery orrated reserve capacity of the battery. For example, if a battery israted as having a particularly robust design with a large reservecapacity, the test criteria can be made more stringent such that anindication that the battery is “good” is only provided if the batterymeets the higher test criteria.

FIG. 2 is a simplified block diagram of tester 10 in accordance withsuch an embodiment. In FIG. 2, tester 10 includes dynamic parametermeasurement circuitry 80 which couples to battery 14 through Kelvinconnections 82. Dynamic parameter measurement circuitry 80 can be anycircuit configuration which measures a dynamic parameter of battery 14.As used herein, a dynamic parameter is one which is related to a signalhaving an AC component. The signal can be either applied directly ordrawn from battery 14. Example dynamic parameters include dynamicresistance, conductance, impedance, admittance, etc. This list is notexhaustive, for example, a dynamic parameter can include a componentvalue of an equivalent circuit of battery 14. Memory 84 is configured tostore a plurality of different test criteria. For example, the testcriteria can be a number of different thresholds or errors which areused to provide an indication as to whether the battery 14 is “good.”Input 54, which can comprise a user input, is coupled to test circuitry86. Test circuitry 86 applies a selected test criteria for memory 84based upon user input 54 to the dynamic parameter measured by dynamicparameter measurement circuitry 80. Based upon this comparison, anoutput is provided. FIG. 2 is a very simplified block diagram and inactual practice a number of the individual elements can be implementedin a single microprocessor and other circuit configurations. Input 64can be any type of input and is hot limited to a user input.

In this aspect of the invention, the criteria used to test battery 14can be adjusted based upon a particular aspect of battery 14. Forexample, if battery 14 is a new battery, a more stringent test can beapplied to battery 14. Additionally, if battery 14 is intended to beused in an industrial vehicle or other situation which is very demandingof a battery, a more “difficult” or stringent test criteria can beprovided. The test criteria can be based upon other factors to thedynamic parameter such as temperature or “static” parameters. The inputfrom input 54 can be any type of input data and does not need to be usergenerated. Example input data includes every make, model, type,construction date, present date, temperature, vehicle type, VIN code,battery service requirements, requirements for a particular application,etc.

Tester 10 can test a battery which is formed by more than one individualbattery. This is called a “battery pack”. For example, some vehiclessuch as large industrial vehicles include multiple batteries which areconnected in series, parallel or series-parallel. In such an embodiment,element 14 in FIGS. 1 and 2 can represent such a pack such batteries canbe particularly difficult to test and, in many prior art batterytesters, have required the batteries to be disconnected and individuallytested.

In accordance with one aspect of the present invention, microprocessor30 tests the multiple batteries using a variety of appropriatetechniques. Microprocessor 30 is capable of determining theconfiguration of the batteries (parallel, series or series-parallel) bymeasuring the voltage at the terminals of the “battery pack” and throughreceiving user input through input 54 indicating the number of batteriesin the pack. Additionally, in some instances microprocessor 30 may alsoneed to receive information related to the voltage of the individualbatteries in the pack in order to make a determination as to theconfiguration of the pack. There are some instances where theconfiguration of the pack cannot be determined by simply knowing thevoltage of individual batteries and taking measurements. A series ofstandard known configurations can be stored in the memory in tester 10tester, and a user can select one such configuration. Configurations ofbattery packs include up to 12 batteries in parallel, three batteries inseries and 12 batteries in series-parallel configurations.Microprocessor 30 is capable of determining the CCA rating and/orconductance of the entire battery pack using the information it hasdetermined regarding the configuration of the battery pack. For example,in parallel configurations the CCA measurement is additive as isconductance, while in series-parallel or series configurations thevoltage can be additive but the CCA/conductance can remain the same.

In one aspect, tester 10 is capable of detecting a good battery, adischarged battery, a bad cell, a bad battery, a marginal and/ordefective wiring within a battery pack without disconnecting the pack.In one such embodiment, multiple test connections are used to connect tothe battery pack. For example, one pair of connections can be used toconnect to either end of the battery pack while another connection canbe used to connect to points within the battery pack or to measurecurrent flowing between points within the battery pack. Using thistechnique, the various currents flowing within the battery pack can bedetermined and this information can be used to detect a bad connection,such as a bad cable or poor physical connection between two pointswithin the battery pack. Additionally, microprocessor 30 can instructthe user using display 32 to make various measurements at various pointsalong the battery pack to more fully determine the condition of variousportions of the battery pack.

In some instances, the microprocessor 30 can instruct the user todisconnect a certain battery within the battery pack in order to performan isolated test on that battery.

In another aspect, microprocessor 30 uses advanced testing criteria ortesting techniques such as fuzzy logic, neural networks or otherartificial intelligence techniques to detect and make decisionsregarding the health of a battery or a battery pack. Such techniques canalso be used in evaluating time varying signals such as signalsgenerated by the operation of alternator 16 or starter 20 in vehicle 12.

In another aspect, tester 10 includes a load such that a traditionalload test can be performed on the battery 14. Such a load test is knownin the art and is performed by applying a load to a battery andobserving the effect of the applied load to the voltage or currentflowing from the battery. In such an embodiment, such information can beused in conjunction with a resistance, impedance, conductance oradmittance test of the battery 14 to identify a defect in the battery orotherwise determine the condition of the battery. This technique canalso be used to measure the remaining or reserve capacity of the batteryor battery pack. Such a testing technique provides additionalinformation to microprocessor 30 which can then be used to make moreadvanced decisions regarding battery condition.

Microprocessor 30 can also compute, store, display or print outequivalent rating information regarding equivalent ratings of battery14. Such equivalent ratings include CCA, SAE, DIN, TEC, EN, CA, MCA, JISor others of the battery. In such an embodiment, microprocessor 30 canadjust for variations in the measured conductance of a battery pack dueto cables between batteries in the pack or the connectors between thecables and the battery which can insert series resistances into themeasurement. The adjustment can be based upon compensation data storedin a memory which is determined empirically by measuring different typesof batteries or through other techniques. Particular compensationinformation can be determined through determining the configuration ofbatteries within a battery pack as described above. The compensationinformation can in the form of a multiplier which is used to multiply aconductance measurement.

In another aspect, measurements of battery conductance are used to“balance” the various batteries in a battery pack such that they areselected and arranged for delivering optimized current and/or receivingoptimized charge current. This aspect is illustrated in FIG. 3. Forexample, if a 600 CCA battery is placed in series with a 500 CCAbattery, one of the batteries will tend to become overcharged while theother battery will tend to be undercharged. Tester 10 can alert anoperator regarding the unbalanced condition of the batteries within thepack. Tester 10 can prompt a user to disconnect certain batteries withinthe pack and perform individual tests on the batteries to determinewhich battery is unbalanced from the others. This will also assist inselecting the batteries used in the battery pack.

FIG. 3 illustrates a simplified diagram of this aspect of tester 10 andincludes a dynamic parameter measurement circuit 80 coupled to battery14 through connection 90. Battery 14 is illustrated as multiplebatteries, in this case three separate batteries 14A, 14B and 14C. Thesebatteries can be connected in series, parallel or series parallel.Connection 90 can be a single pair of Kelvin connectors which areselectively positioned between or on various batteries in pack 14. Therecan be more than two Kelvin connections which are coupled to pack 14.Memory 94 stores a first dynamic parameter from dynamic parametermeasurement circuit 80 related to a dynamic parameter of at least onebattery 14A, 14B or 14C within battery pack 14. Balance circuit 92provides an in-balance output if a second dynamic parameter of a secondbattery or batteries within pack 14 is “substantially equal” to thedynamic parameter stored in memory 94. As used in this context, the term“substantially equal” means that the two dynamic parameters are within apredetermined or adjustable percentage or fixed amount from one another.If the two dynamic parameters are measured simultaneously, memory 94 isnot required to store a dynamic parameter. In a further embodiment ofthis aspect of the invention, a static parameter such as voltage is usedin determining if the batteries are within balance. For example, the twobatteries are within 0.1 volts of each other (i.e., 12.5 and 12.6 volts)and the conductance within 10%, an in-balance indication is provided. Inanother example, less than a 0.05 volt difference is required inaddition to the dynamic parameter requirement. Additionally, data frommultiple batteries can be stored in memory 94 and a preferredconfiguration of the batteries can be provided by balance circuitry 92on its output. Information regarding the configuration of battery pack14 can be received through the input 54 shown in FIGS. 1 and 2 and theoutput from balance circuit 92 adjusted accordingly.

The condition of cables or connectors can be determined by applying alarge load, such as through an internal load in battery tester 10 orthrough application of a vehicle load 18, or through the application ofa large resistance, for example more than about 0.1 ohms. An amp clampmeasurement can also be used. Further, microprocessor 30 can prompt auser to measure voltage drops across various cables in the pack and makea decision (i.e., good/bad) regarding a cable or connection in thebattery pack. Microprocessor 30 can store, display, print and managemultiple test results associated with the multiple test measurementsmade when measuring a number of batteries which make a battery pack.This can be partial measurement, parameter, or other items related toindividual batteries within the pack.

In one aspect, battery tester 10 is configured to determine the CCArating of a battery or battery pack having a relatively large CCA value,for example, up to 5000 CCA. In such an embodiment, sensitive amplifiersand/or relatively large current values can be used to obtain the CCA orconductance measurement. In another aspect, tester 10 can perform a teston vehicle 12 by instructing an operator to apply a load (i.e., headlights, blower, etc.) or a combination of loads and preserve theresponse from battery 14. This information can be used to determinediagnostic information regarding battery 14 out of the operation ofcomponents within vehicle 12.

With one aspect of the invention, the tester can be used to test the“straps” that are used to couple individual batteries together to forma-battery pack. For example, a dynamic parameter can be measured withthe Kelvin probes applied directly to the battery. A second dynamicparameter can be measured in which one of the straps separates a Kelvinprobe from the battery. A microprocessor can then compute the dynamicparameter of the strap alone and provide an output if the strap is poor.For example, if the strap dynamic conductance is too low, a warning canbe provided. This technique can be extended to test multiple straps. Inaddition to testing straps within the pack, this technique can also beused to test cables that connect to the battery. Dynamic parameters canbe stored in the memory for use in subsequent computations or multipleKelvin probes can be used to simultaneously measure multiple dynamicparameters.

In some aspects, a separate current probe can be used, such as a shunt,amp clamp or Hall effect sensor, to measure the current flowing into orout of a battery or group of batteries under test. This data can bepaired with voltage measurements to obtain static or dynamic parameters.

The tester can store measurements in memory such that the battery packcan be ranked in terms of performance.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. An electronic battery tester for use in testing a battery pack formedby a plurality of storage batteries, comprising: battery test circuitryconfigured to measure a dynamic parameter of the battery pack formed bythe plurality of batteries using Kelvin connectors coupled to thebattery pack and provide a battery test result; a memory configured tostore a plurality of known configurations (series, parallel andseries-parallel) of batteries in a battery pack; a microprocessorconfigured to automatically identify the configuration (series, paralleland series-parallel) of the plurality of batteries in the battery packbased upon a measured voltage of the battery pack and responsivelychange a test criteria of the battery test circuitry; and wherein thebattery test result is based upon the identified configuration of theplurality of batteries.
 2. The apparatus of claim 1 wherein themicroprocessor determines battery pack configuration further as afunction of a user input.
 3. An electronic battery tester for use intesting a battery pack formed by a plurality of storage batteries,comprising: battery test circuitry configured to measure a dynamicparameter of the battery pack formed by the plurality of batteries usingKelvin connectors coupled to the battery pack and provide a battery testresult; a memory configured to store a plurality of known configurations(series, parallel and series-parallel) of batteries in a battery pack; amicroprocessor configured to identify the configuration (series,parallel and series-parallel) of the plurality of batteries in thebattery pack based upon a user input and responsively change a testcriteria of the battery test circuitry; and wherein the battery testresult is based upon the identified configuration of the plurality ofbatteries.
 4. The apparatus of claim 3 wherein the microprocessordetermines battery configuration further as a function of a measuredvoltage of the battery pack.
 5. The apparatus of claim 4 wherein themicroprocessor is further configured to identify a configuration of theplurality of batteries in the battery pack based upon a voltage ofindividual batteries in the battery pack.
 6. The apparatus of claim 3wherein the user input is configured to select one of the plurality ofstandard known configurations stored in the memory.
 7. The apparatus ofclaim 3 wherein the microprocessor determines a CCA rating of thebattery pack based upon the battery test result and the identifiedconfiguration of the plurality of batteries in the battery pack.
 8. Theapparatus of claim 3 wherein the microprocessor determines a conductanceof the battery pack based upon the battery test result and theidentified configuration of the plurality of batteries in the batterypack.
 9. The apparatus of claim 1 including a memory configured to storea plurality of standard known configurations of battery packs.
 10. Theapparatus of claim 1 wherein the microprocessor is further configured toidentify a configuration of the plurality of batteries in the batterypack based upon a voltage of individual batteries in the battery pack.11. The apparatus of claim 2 wherein the user input is configured toselect one of a plurality of standard known configurations stored in thememory.
 12. The apparatus of claim 1 wherein the microprocessordetermines a CCA rating of the battery pack based upon the battery testresult and the identified configuration of the plurality of batteries inthe battery pack.
 13. The apparatus of claim 1 wherein themicroprocessor determines a conductance of the battery pack based uponthe battery test result and the identified configuration of theplurality of batteries in the battery pack.